Electric resistance element.



A. L. MARSH.

ELECTRIC RESISTANCE ELEMENT. APPLICATION FILED MAR. 15, 1905.

PATENTED FEB. 6, 1906.

UNITED sTA s P ENT OFFICE.

ALBERT L. MARSH, or LAKE BLUFF, ILLINOIS, ASSIGNOR To THE HOSKINSCOMPANY, ILLINOIS.

OF CHICAGO, ILLINOIS, A CORPORATION OF ELECTRIC RESISTANCE ELEMENT.

To all whom it may concerts.-

Be it known that I, ALBERT L. citizen of the United States,

lufi, in the county of Lake and State of Illinois, have invented a newand useful Improvement in Electric Resistance Elements, of. which thefollowing is a specification.

My object is to provide, as an improved electric resistance material, ametal which has the property of being particularly low in electricconductivity, has a meltingoint exceeding that of pure copper, and may edrawn or otherwise shaped to form particularly durable, efficient, anddesirab or filaments suitable for use in the various connections whereelectric sirable.

I have discovered that the metals of what is termed the chromium group,particularly when mixed with nickel, form an alloy having the propertiesof being very low. in electric cond dizable to MARSH, a residing at Lakeresistances are dea ve gh degree, tough and sufficientlyduetile topermlt drawing or shapelectric resistances, ta

we b loy consisting of ninety per cent. nickel and,

ing it into wire or strip form to render it con-' vement for use as anelectricresistance elementi" The chromium group herein referred to,asdefined, for example, in cry of Ohem'ist consists of the metallic ele'ments of oup %o.. VI, (indicated by the even numbere series,) accordingto what is generally desi nated asMendelefis table. (See page 212,emsens Chemistry, fifth edition, Hen Holt & 00., New York 1898.) Thesemeta s are chromium, moly denum, tun sten, and uranium. Any one of thesemeta s is suitable for my ous reasons I prefer to employ chromium.Uranium at the present time is so rare and expensive as to render itsgfineral use for my purpose commerclally pro 'bitive. As the abovemetals possess characteristics in commen which adapt them to m purpose,any one of them may be employe though when alloyed with nickel orcobalt, for example, proportions may va to produce the best thenecessary toughness and ity desirable for the particular purp ese in d.a I have found, for example,

that an alten per cent. mommercrally. pure may be drawn into a fine wireand producing a tough metal chromium annealed, a meltingle strips,strands,

uctivity, very infusible, non-oxi' Watts Dilation.

purpose, though for vari-.

g into consideration" degree, of ductil r Specification of LettersPatent. Application filed Inch .15, 1905- Serial No. 260,309;

Patented Feb. 6, 1906.

point exceeding that of pure copper and with an electric re istanceapproximating fifty times that of ure copper. Its temperaturecoefficient is particularly low, it does not become crystalline andbrittle under heating and coolmg, it resists oxidation to a remarklikewise keeps a polish under all atmospheric conditions, even wherecorrosive fumes are present. Any metal of the chromium group .possessesdesirable qualities for electric resist ance material whether employedalone or alloyed with nickel or cobalt. At the present time I am of oinion that the most practical and desirable e ectric resistance materialmay be formed of an alloy of nickel and chromium in suitable proportiondrawn into strips, strands, or filaments and annealed, In its broadestsense, however, my invention is not to be limited to an alloy of thelast-named metals.

The accompanying drawing shows a rheo stat of a well-known type in whichthe coiled wires a are resistance elements formed of a metal alloy,consisting of less than fifty per cent. of'a metal of the chromium groupand more than fifty per cent. of nickel or cobalt, or both. In practiceI prefer, commercial reasons, to form the alloy of preferably less thantwenty five per cent. chromium and more than seventy-five per cent.nickel. Variations in the relative proportions of the metals wouldaffect more or "less able degree under vervhigh temperature, and

mainly for the variations in strength, durability, and resistivit of thealloy. It may be stated. for examp e, that a metal alloy consistin offifteen pe cent. chromium cent. nickel drawn into a wire sixteenonethousandths of an inch in diameter has a resistance ap roximatin 2.3ohms per foot.

As state before, eit or nickel or cobaltis suitable for m purpose whenalloyed with a metal of the cliromium group in a proportion of more thanfifty or both, and less t mium or the like.

per cent. nickel or cobalt, han fifty per cent. chro- Nickel and cobaltalloy readily with metals of the chromium group and resist oxidation to0. hi h degree. Iron, on the other hand, is read y oxidizable and willnot answer my purpose when alloyed with a metal of the chromium ere Imention in the claims a meta hav- .mg the properties of nickel orcobalt, I wish to roup.

ve per too designate only the metals nickel and cobalt, which haveproperties that are the same for my purpose, but which cannot bothbeclassed under an single term of which I am aware.

What claim as new, and desire to secure by Letters Patent, is-

1. An electric resistance element composed of a metal alloy consistingofone of the metals of the chromium group, in the proportion of less thanfifty per cent. of the element, and more than fifty per cent. of metalhaving the properties of nickel and cobalt.

2. An electric resistance element comprising a strip, strand or filamentformed of an alloy of nickel and one of'the metals of the chromiumgroup.

3. An electric resistance element comprising an annealed strip, strandor filament formed of an alloy of nickel and one of the metals of thechromium group.

4. An electric resistance element formed of a metal alloy consisting ofnickel and chromium.

5. An electric resistance element formed of a metal alloy consisting ofchromium in the proportion of less than fifty per cent. of the elementand nickel in the proportion of more than fifty per cent. of theelement.

ALBERT L. MARSH. 1n presence of J. ll. LANDns, J. ll. LEE.

